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Blood and gut virome remodeling in gastric cancer: Anellovirus expansion and novel virus discovery.

Gastric cancer (GC) is a prevalent malignancy worldwide, yet effective early diagnostic tools remain lacking, and the role of the virome, a key component of the tumor microenvironment, in GC progression is largely unknown. This study aimed to characterize the virome landscapes in peripheral blood and feces of GC patients versus healthy controls, and to identify viral signatures associated with GC onset and metastasis. We performed viral metagenomic sequencing on pooled libraries from 100 GC patients (45 non-metastatic, 55 metastatic) and 50 healthy controls, followed by taxonomic annotation, diversity assessment, LEfSe differential abundance testing, and co-occurrence network analysis. In blood, the GC virome shifted from a bacteriophage-dominated profile in controls to one overwhelmingly dominated by Anelloviridae (> 80%), with significantly decreased alpha diversity. In contrast, the gut virome of GC patients showed increased alpha diversity and coexistence of diverse bacteriophages. LEfSe identified betatorquevirus in blood as a key discriminatory taxon for GC. Network analysis revealed negative correlations between Anelloviridae and multiple bacteriophage families, suggesting niche competition. We also discovered 67 provisional novel anellovirus species and one novel gemykibivirus in GC patient blood. Collectively, our findings indicate that GC is associated with compartment-specific virome remodeling in blood and gut, and that expansion of blood anelloviruses holds promise as a non-invasive biomarker. This study provides a foundational resource for understanding the virome's role in GC.

Humans

Deep Characterisation of Circulating Torque Teno Virus DNA Load in Crohn's Disease Patients.

Torque teno virus (TTV) DNA load in plasma is suggested as a marker for immunosuppression post-transplantation. Crohn's disease (CD) arises from genetic susceptibility, environmental factors, and dysbiosis, causing immune responses. This study examines TTV DNA load in CD patients in remission and its correlation with relapse. Using quantitative real-time polymerase chain reaction (PCR) and metagenomic analysis, the dynamic of plasma TTV DNA load was analyzed from a cohort of CD patients (n = 39) over 1 year and compared with controls (n = 49). At inclusion, TTV DNA was significantly higher in CD patients compare to control (Median [IQR]: 3.27 [2.43-3.67] and 2.05 [1.28-2.80] Log copies/mL, p = 0.0004). Plasma TTV DNA load failed to predict disease relapse in CD patients. Augmented plasma TTV DNA levels in CD patients correlated with diminished circulating CD3 + T cells and especially CD4 + T cells. No preferential representation of TTV subspecies or Anelloviridae genera was detected in CD patients' plasma. This study revealed elevated TTV DNA levels in CD patients' plasma compared to healthy controls, underscoring the intriguing potential of TTV blood sampling as a biomarker in CD.

Humans

Transmission of Anellovirus From Kidney-Donor to Pediatric Recipient: An Exploratory Study.

BACKGROUND: Among the most abundant viruses in the human blood virome are anelloviruses, including alpha-, beta-, and gammatorqueviruses (TTV, TTMV, and TTMDV). Whether anelloviruses are transmitted through kidney transplantation at a young age and subsequently persist in their new host is unknown. This study investigates the dynamics and composition of the anellome in the blood of six pediatric donor-recipient pairs, with monitoring beginning before transplantation and continuing until 2&#x2009;years after transplantation. METHODS: Donors were sampled once, before donation, while recipients were sampled before and multiple times after transplantation (median 6.5 samples). Quantitative PCR, rolling circle amplification, Illumina sequencing, and SCANellome V2 analysis were used to detect, characterize, and compare anellovirus presence in donors and recipients. RESULTS: At baseline, four out of six donors tested positive for TTV by quantitative anellovirus PCR, three of whom had sufficient viral loads to enable genomic comparison with their recipients. All recipients tested positive at baseline, five had a moderate viral load (<&#x2009;105 copies/mL), and one had >&#x2009;109 copies of TTV DNA/mL. This recipient was already immunosuppressed before transplantation, and only in this recipient was a donor-derived anellovirus identified. This lineage was detected among 15 other lineages in the recipient and matched one of the four lineages identified in the donor. CONCLUSION: This finding demonstrates that anellovirus transmission from donor to recipient occurs in pediatric kidney transplantation. This may be associated with pre-existing immunosuppression.

Humans

Discovery of diverse anellovirus sequences in Thai human sequencing data.

UNLABELLED: Anelloviruses are part of the normal human viral flora. Although their diversity in humans has been investigated in many countries, and despite their initial detection in Thailand in 1999, knowledge of Thai anelloviruses remains very limited. This study analyzed 1,175 whole-genome sequencing data sets from Thai individuals to mine for potential anellovirus sequences. Our analyses detected anellovirus sequences in 149 data sets (12.68%), uncovering 434 partial anellovirus sequences and 77 complete genome sequences, characterized by the presence of terminal redundancy, complete orf1, and the conserved untranslated region upstream of the orf1 gene. Sequence analyses indicated that these viruses belong to seven genera, including Alphatorquevirus, Betatorquevirus, Gammatorquevirus, Hetorquevirus, Lamedtorquevirus, Samektorquevirus, and Yodtorquevirus. Notably, Hetorquevirus, Lamedtorquevirus, Samektorquevirus, and Yodtorquevirus had not previously been reported in Thailand. Phylogenetic analysis of ORF1 protein sequences showed that Thai anelloviruses form multiple phylogenetic clusters with non-Thai anelloviruses, indicating frequent cross-country transmission and multiple origins of the virus in Thailand. Furthermore, sequence similarity network analysis identified 33 potentially novel anellovirus species in our data set. Our findings greatly expand the knowledge of anellovirus diversity in Thailand and demonstrate the potential of human whole-genome sequencing data as a valuable resource for viral discovery. Lastly, we highlight and discuss some challenges with the use of the current pairwise sequence similarity-based classification scheme, in particular, how gaps can influence similarity calculation and potentially lead to inconsistencies with a phylogenetic-based classification scheme. IMPORTANCE: Anelloviruses are widespread in humans, yet their diversity remains poorly characterized in many regions, including Thailand. Here, we demonstrate that human sequencing data sets, originally generated without the intention for virome research, can be effectively mined for anellovirus sequences, including complete genomes. Our findings reveal a substantial number of previously unreported anelloviruses in Thailand, significantly expanding the known diversity of the virus. We also highlight potential limitations of the current anellovirus species classification scheme, which is based on pairwise orf1 sequence similarity analysis with a hard threshold cutoff at 69%. Our results reveal that the current scheme can sometimes yield taxonomic groupings that are inconsistent with phylogenetic relationships, particularly when significant alignment gaps are present. Overall, our results show that existing human sequencing data can be effectively repurposed for virus discovery research and suggest the need for more robust and phylogenetically informed classification frameworks as viral sequence databases continue to expand.

Humans